Carburetor step-up device



\ 1 D. Vr-:coYcE CARBUHETOR STEP-UP DEVICE Filed Feb. 7, 1939 ,June 11,

Patented June 1l, 1940 CARBURETOR STEP-UP DEVICE Leonard D. Boyce, Maplewood, Mo., assignor to Carter Carburetor Co rporation, St. Louis, Mo.,

a corporation of Delaware Application February 7, 1939, Serial No. 255,153

1 Claim.

This invention relates to carburetors for internal combustion engines and particularly to the means for enriching the mixture when the associated engine is subjected to a relatively heavy load.

Most automotive carburetors4 now in use` are provided with means for supplying additional fuel to the engine intake when the engine is subjected to a relatively heavy load. Such means may take the form of a suction operated device for supplying the additional mixture when relatively low suction conditions prevail in the mixture conduit,`

or the enriching device may be operated mechanically from the throttle valve. The step-up may comprise an extra metering jet in the carburetor float bowl, controlled either by a suction device or by the throttle, or it may constitute a metering pin or rod associated with the main metering jet and stepped or tapered to enrich the mixture as desired. Under most operating conditions, the carburetor will operate satisfactorily without using the extra mixture which is supplied by the step-up device, since this device is necessary only under extremelload conditions to permit the engine to develop its maximum horse power. The operator may prevent the operation of either a mechanical or suction step-updevice by limiting the degree to which `the throttle valve is opened, but it is practically impossible for the operator to determine this point while driving a car. Obviously,l greater economy could be obtained if means were provided'to prevent operation of the stepup except when it is absolutely necessary.

Accordingly, the object of the present invention is to provide means for indicating to the operator of a vehicle, theloperative condition of the step-up device so that, in case maximum economy is desired, he may refrain from opening the throttle valve beyond the position where the step-up is rendered operative.

This object and other more detailed objects hereafter appearing are obtained substantially by the device illustrated in the' accompanying drawing in which:

Fig. 1 is a vertical transverse section illustrating a carburetor embodying the invention.

Fig. 2 is a View of a'portion of the structure shown in Fig. 1, but with parts in different operative positions.

The carburetor shown includes an air horn I, venturis 2, and outlet portion 3 forming a mixture conduit, the outlet portion being anged as at 4 for attachment to the intake manifold (not shown) of an associated internal combustion en- 55 gine. A choke valve 5 is mounted in the air horn and a throttle valve 6 is located near the outlet portion. Adjacent the mixture conduit is a bowl 1 within which fuel is maintained at a substantially constant level by the usual needle valve mechanism 8 controlled by a float 9. Fuel for 6 normal operation is supplied to the mixture conduit through a calibrated metering orifice member I0 and main nozzle II terminating at the throat of upper venturi 2.

There is also provided a suction step-up device l0 including an additional orifice member I2 opening into the main nozzle passage and controlled by a needle I3 extending through a guide I4 and secured at its upper end through a coiled spring I5 to a strap I6. Adjacent needle I3 is a cylinder l5 I'I communicating through passage I8 with the carburetor mixture conduit posterior to throttle 6. A piston I9 is slidable in cylinder I'I and constantly urged upwardly by a coiled spring 2li. Strap I6 is secured to piston I8 whereby needle I3 20 reciprocates vertically with piston I9 responsive to suction conditions in the mixture conduit. The various parts are constructed so that when the engine intake suction drops below a predetermined value, on the order of two inches of mercury, spring 20 will force piston I9 and needle I3 upwardly, opening auxiliary orifice member I2 to supply additional fuel to the mixture conduit.

Slidably mounted in a bearing 2|, carried by cover portion 22 of the float bowl, is a reach pin `30 23 which rests on piston I9 and terminates, when piston I9 is depressed below a metal strap 24 carried by a block 25 of insulating material projecting above the bowl cover (Fig. 1). Strap 24 is electrically connected by means of lead 26 to an 35 electric light 2'I and through lead 28 to battery 29, grounded at 30. Reach pin 23 is grounded through the carburetor and engine so that when this pin is moved into Contact with strap 24 (Fig. 2), as when the suction step-up device is operative to enrich the mixture, a circuit will be completed through lamp 21 so as to aord a visual indication of the operative condition of the stepup. Preferably, lamp 2l is located on the dash of the automobile or at another position readily 45 visible to the operatorfrom the driving seat.

If desired the indication may be audible instead y of visual and this may be effected by means of a suitable buzzer or other noise maker. I also contemplate using the device with any type of step- 50 up mechanism which includes a member movable when the auxiliary fuel supply means is rendered operative, this member being arranged to actuate the indicator means.

Various features of the carburetor are not essential and the indicating mechanism may be varied as Will occur to those skilled in the art. The exclusive use of all modications as come within the scope of the appended claim is contemplated.

I claim: y

In combination with an internal combustion engine intake conduit, a manually actuated in said conduit when the suction therein has reached a predetermined value, an opening in the cover of said oat bowl, a guideway positioned adjacent said opening, said guideway and the walls of said opening being in vertical alignment with said plunger, a grounded reach pin arranged to travel in said guideway'and to extend into the bowl of said carburetor for normal engagement with said plunger and movement therewith, an insulated support on said bowl, a contact element carried by said support for engagement with said reach pin at a point in its travel determined by the open position of said valve in said auxiliary fuel passage, and an indicator circuit connected with said contact whereby the passage of auxiliary fuel to the conduit will be indicated to permit the relative regulation of the' manually actuated throttle.

' LEONARD D. BOYCE. 

